Role of phosphopyridoxamine oxidase gene pnpox in Stenotrophomonas acidaminiphila

Abstract:

[Objective] To reveal the role of the phosphopyridoxamine oxidase gene pnpox in vitamin B₆ (VB₆) synthesis and aflatoxin B1 (AFB1) degradation in Stenotrophomonas acidaminiphila CW117. [Methods] The phosphopyridoxamine oxidase gene was mutated in strain Stenotrophomonas acidaminiphila CW117 by the recombinant plasmid pK19mobΩ2HMB/P-pnpox, and thus the mutant pnpox::pK19mobΩ2HMB was constructed. The vitamin B₆ (i.e., pyridoxine and pyridoxal) synthesis and AFB1 degradation activities of the mutant and the wild-type strain CW117 were detected by high performance liquid chromatography (HPLC). The detemination results were compared to reveal the role of pnpox in VB₆ synthesis and AFB1 degradation. [Results] The mutant pnpox::pK19mobΩ2HMB was successfully constructed. It had significantly lower yield of pyridoxal than the wild-type strain CW117, while no significant difference was observed in the yield of pyridoxine between the mutant and CW117. Meanwhile, the mutant showed no significant difference in AFB1 degradation from CW117.[Conclusion] Phosphopyridoxamine oxidase plays an important role in the pyridoxal synthesis of CW117. The mutation of pnpox reduced the VB₆ production and thus seriously delayed the growth of the strain, while the gene showed no significant contribution to AFB1 degradation in strain CW117.